1. Field of the Invention
The present invention relates to an error-correction apparatus for a step motor transmission system and a method for the same, and especially to an error-correction apparatus for correcting step error in a step motor-transmission system and a method for the same.
2. Description of Prior Art
The digital electronic products are prevalent in modern ordinary life. Among them, the high-end digital still camera and scanner have been developed to use a step motor to enhance image quality. More particularly, the transmission system of a step motor is under intense research to provide precise control.
The step motor comprises a plurality of precise inductor coils to control precise rotation of internal shaft in the step motor. Therefore, the step motor can provide precise moving displacement. Taking a high-end scanner as an example, the image quality thereof depends not only on a CMOS sensor thereof but also on the precise displacement pitch provided by the step motor.
FIG. 1 shows a driving circuit for a conventional 2-phase step motor 10. The step motor 10 comprises two sets of inductor coils 11 connected to two sets of driving circuits 12, a digital-to-analog converter (DAC) 13 and a processor 14. The processor 14 sends a digital displacement signal to the DAC 13 and the DAC 13 converts the digital displacement signal into two sets of control currents for sending to the two sets of driving circuit 12, respectively. The inductor coils 11 are driven by the control currents to generate magnetic excitation for rotating the internal shaft in the step motor.
However, the high-end step motor 10 generally is expensive and the transmission system thereof still has a certain amount of error, which results from fabrication error in the f inductor coil 11. A time-consuming post-correction is thus needed.